Re: [PATCH v5 5/8] kbuild: add fine grained build dependencies for exported symbols

From: Nicolas Pitre
Date: Sun Mar 06 2016 - 01:20:30 EST


On Sat, 5 Mar 2016, Nicolas Pitre wrote:

> On Sat, 5 Mar 2016, Michal Marek wrote:
>
> > I reproduced the SIGBUS after a few iterations, and it crashes in
> > parse_dep_file(). I'm now testing this
> >
> > diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> > index 0be7e09ba381..4fdd8348acf6 100644
> > --- a/scripts/Kbuild.include
> > +++ b/scripts/Kbuild.include
> > @@ -270,10 +270,12 @@ else
> >
> > # Filter out exported kernel symbol names from the preprocessor output.
> > # See also __KSYM_DEPS__ in include/linux/export.h.
> > +# We disable the depfile generation here, so as not to overwrite the existing
> > +# depfile while fixdep is parsing it
> > ksym_dep_filter = \
> > case "$(1)" in \
> > - cc_*_c) $(CPP) $(c_flags) -D__KSYM_DEPS__ $< ;; \
> > - as_*_S) $(CPP) $(a_flags) -D__KSYM_DEPS__ $< ;; \
> > + cc_*_c) $(CPP) $(filter-out -Wp$(comma)-M%, $(c_flags)) -D__KSYM_DEPS__ $< ;; \
> > + as_*_S) $(CPP) $(filter-out -Wp$(comma)-M%, $(a_flags)) -D__KSYM_DEPS__ $< ;; \
> > cpp_lds_S) : ;; \
> > *) echo "Don't know how to preprocess $(1)"; false ;; \
> > esac | sed -rn 's/^.*=== __KSYM_(.*) ===.*$$/KSYM_\1/p'
>
> This makes perfect sense even if I can't reproduce on my side.

I folded the following patch into my tree and pushed it out.

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 0be7e09ba3..2c14a27e39 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -270,14 +270,17 @@ else

# Filter out exported kernel symbol names from the preprocessor output.
# See also __KSYM_DEPS__ in include/linux/export.h.
+# We disable the depfile generation here, so as not to overwrite the existing
+# depfile while fixdep is parsing it
+flags_nodeps = $(filter-out -Wp$(comma)-M%, $($(1)))
ksym_dep_filter = \
case "$(1)" in \
- cc_*_c) $(CPP) $(c_flags) -D__KSYM_DEPS__ $< ;; \
- as_*_S) $(CPP) $(a_flags) -D__KSYM_DEPS__ $< ;; \
+ cc_*_c) $(CPP) $(call flags_nodeps,c_flags) -D__KSYM_DEPS__ $< ;; \
+ as_*_S) $(CPP) $(call flags_nodeps,a_flags) -D__KSYM_DEPS__ $< ;; \
cpp_lds_S) : ;; \
- *) echo "Don't know how to preprocess $(1)"; false ;; \
+ *) echo "Don't know how to preprocess $(1)" >&2; false ;; \
esac | sed -rn 's/^.*=== __KSYM_(.*) ===.*$$/KSYM_\1/p'
-
+
cmd_and_fixdep = \
$(echo-cmd) $(cmd_$(1)); \
$(ksym_dep_filter) | \

Nicolas